Method of making double-faced corrugated board having a tear strip therein



June 26, 1956 R. GUYER 2,751,964

METHOD OF MAKING DOUBLE-FACED CORRUGATED BOARD HAVING A TEIAR STRIP THEREIN Filed April 13, 1953 2 Sheets-Sheet 1 "1 I 2a 6 25 I 27 I 2; 50 1 1 n? -I 3 I i l I 16 10 h z; i 2 2 Uf Z! 22 23 4 INVENTOR Z3 Reyna/d5 Gaye)" 5 7- 3 BY Q w a ATTORNEY June 26, 1956 R. GUYER 2,751,964

METHOD OF MAKING DOUBLE-FACED CORRUGATED BOARD HAVING A TEAR STRIP THEREIN Filed April 15, 1953 2 Sheets-Sheet 2 INVENTOR Fe 270/415 641 er y 9 ATTORNEY Unite tates METHOD OF MAKING DGUBLE-FACED CO GATED BOARD HAVING A TEAR STRIP TEREIN Reynolds Guyer, St. Paul, Minn, assignor to Waldorf Paper Products Company, St. Paul, Minn, a corporation of Minnesota Application April 13, 1953, Serial No. 348,413 Claims. (Cl. 15433.05)

This invention relates to an improvement in tear strip constructions and deals, particularly, with a method and apparatus for forming a tear strip in corrugated board.

In my previous filed application, Serial No. 385,586, filed October 12, 1953, a continuation in part of which eventuated into Patent 2,706,076, for Container Opener, I described a container structure which included a pair of weakened lines, or cut lines, extending transversely of the corrugations of the board. These cut lines were normally provided in the liner forming the inner surface of the container formed of corrugated board or could, if preferred, be provided in both the inner and outer liners with the cut lines of the two liners opposed, or sub stantially opposed. Prior to filing the above mentioned application, I discovered that by forming a pair of closely spaced cut lines in the inner liner of a piece of corrugated board, and by pulling outwardly on this portion of the board, the strip between the cut lines on the inner liner would cut through the corrugated center portion of the board and the outer liner of the board to separate the container into two parts.

An object of the present invention lies in a method of forming board of the type previously described. In this method, the inner liner is completely cut through or partially cut through, before the corrugated board is assembled, thereby preventing any damage of crushing or otherwise injuring the corrugated center portion of the board.

A further feature of the present invention resides in the provision of a paper slitting or perforating means supported in the path of movement of one of the liners of corrugated board prior to the time this liner is combined with the corrugated center portion of the board. As a result, the liner may be completely out through to provide a strip extending longitudinally of the sheet and which may later form a tear strip in the container formed from the corrugated board.

A further feature of the present invention resides in providing a pair of slitting or perforating knives in the path of movement of one or both of the liners just prior to the time the liners are adhered to the corrugated center portion of the board. Accordingly, the severed portion of the sheet is adhered to the corrugated portion thereof directly after the slitting operation, thus insuring the proper positioning of the cut portion of the sheet relative to the remaining portion thereof.

A further feature of the present invention resides in the fact that a plurality of pairs of slitting knives may be provided in place of the single pair described. In the formation of corrugated containers, it is common practice to cut the corrugated board formed to approximately the proper blank size as it leaves the corrugated board-forming machine. As a result, it is commonplace to simultaneously form two or more containers in the width with sheet being formed. In such event, a pair of slitting rollers may be provided for each container so that each of the containers may be provided with its own tear strip.

An added feature of the present invention resides in the 2,751,964 Patented June 26, 1956 provision of a method of forming a tear strip on sheets of corrugated board by cutting a strip in one of the liners as the liner enters the corrugator for attachment to the corrugated inner sheet. This process is therefore continuous and insures the proper positioning of the tear strip in the finished sheets.

These and other objects and novel features of my invention will be more clearly and fully set forth in the following specifications and claims in the drawings forming a part of my specification.

Figure 1 is a diagrammatic view of a carton blank showing the tear strip formed therein.

Figure 2 is an enlarged sectional view through a portion of the tear strip, the portion of the section being indicated by the line 22 of Figure l of the drawings.

Figure 3 is a perspective view of a container having a tear strip in partially opened form.

Figure 4 is a diagrammatic view showing the passage of paper sheets through a corrugator and showing one position in which the cutting or slitting knives may be mounted.

Figure 5 is a diagrammatic view showing the slitting knives cutting the inner liner of the board.

Figure 6 is a view similar to Figure 2, showing a modified construction.

Figure 1 shows diagrammatically the blank of a regular corrugated container having a tear strip therein. The container is shown as having wall panels 16, i1, 12 and 13 which are separated by parallel fold lines 14, 15 and 16. The upper edges of the container wall panels are connected along a common line of fold 18 to closing flaps i5, 16, 17 and 19 respectively. The lower edges of the container walls are connected along a common line of fold 26 to bottom closing flaps 21, 22, 23 and 24 respectively. This particular arrangement is shown for the purpose of illustration as virtually any type of container may be employed.

As illustrated in Figure 1 of the drawings, a pair of parallel cut lines 25 and 26 extend transversely through the wall panels 10, 11, 12 and 13 parallel to the fold lines 13 and 20. These cut lines 25 and 26 define a relatively narrow strip 27 therebetween which forms the inner layer of the tear strip. In actual practice the portion of the container adjoining the ends of the tear strip 27 may be printed as indicated at 29 and 30 so that the tape used to join the free ends of the wall panel 10 and 13 will not adhere to the tear strip. The areas 29 and 30 are shown in dotted outline as the printed a eas are on the outside of the container while the cut lines 25 and 26 are on the inside thereon.

Figure 2 of the drawings indicates in enlarged cross section the manner in which the cut lines 25 and 26 extend through the inner liner 31 of the sheet. The outer liner 32 as well as the corrugated center portion 33 remain uncut in preferred form of the invention. In modified form, the outer liner 32 may be cut in place of the inner liner 31 or both liners 31 and 32 may be cut, the corrugated center portion 33 remaining uncut. This is described in the previous application mentioned above and shown in Figure 6. Parallel cut lines 28 are shown in Figure 6 spaced slightly farther apart than the opposite cut lines 25 and 26. Alternatively, these lines could be directly opposed to the out lines 25 and 26.

Figure 3 of the drawings shows the tape strip 34 joining the end edges of the panels 10 and 13 and shows the tear strip 27 partially removed from the wall panel 13. As is clearly indicated in this View, the cutting of the inner liner is advantageous as this cut strip 27 acts to shear olf the corrugated center portion 33 and the outer liner 32 as the strip is pulled outwardly. In constructions where only the outer liner is cut, the tear strip should preferably be removed by an inward pull upon the 3 proper portionof'the"container, this arrangement being normally impossible with -acontainer ofusual type when filled.

In the present invention the inner liner 31 is preferably cut by slitting knives-35 mounted npon a-shaftfio extending transversely of the liner 31. As will'be obvious from an examination of Figure of the drawings, the shaft 36 may be supported by suitable bearings 37 mounted on V opposite sides of the sheet and the shaft may support any desired number of slitting wheels. In preferred form the slitters on the shaft 36 work in conjunction with, and against, a hardened mandrel roll 3d on the corrugator and the slitting knives maybe rotated by movement of the liner but may be power driven. While slitting wheels provide a common means of cutting paper board and are preferred in the present invention, stationary slitting knives have also been used with success.

With reference to Figure 4 of the drawings, the liner 31 r preferably supported between the rolls 42 and 43 so as to slit the sheet shortly before it is adhered to the corrugated center sheet 33.

The sheet 33 which forms the corrugating medium extends from the supplyroll 45 over, the'feed roll 46 and to the corrugating roll 47 which cooperates with the corrugating roll 44 to crimp the paper therebetween into corrugated form. As the corrugated sheet passes bewhich transfers glue from the glue Wheel 5ft to the surface of thecorrugations. Just after the glue is applied, the corrugated sheet is adhered to the liner 31 in the usual manner. The foregoing description varies somewhat in corrugators of various types. However this description is typical of a manner in which the liner 31 and the sheet 33 may be adhered together to form single faced corrugated sheet. This corrugated sheet is guided between conveyers 51 and 52 to elongated conveyer 53 on which the sheet is looped to provide suflicient time fordrying.

As. is usual practice, the single-faced sheet, indicated by the numeral '54 is guided downwardly between a pressureroller 55 and a glue wheel'56 which acts to apply glue. or other adhesive to the corrugations of the single face. The .outer' liner 32 is guided from a supply roll 57 over a suitable preheating roll 59 to a feed roll 60 which directs the sheet between pressure rollers 61 and 62 which joins the liner 32 to the single-faced sheet 54.

If desired, a second slitter shaft 63 may be provided between the feed roll 69 and the pressure roll 62'and' this shaft 63 may support slitters 64 which will rotate either separately from or in conjunction with the slitter knives 35 previously described. Theseslitter knives 64 maybe rotatedin any conventional manner to cut a strip of paper board from the liner 32 and are only used when it is desired to cut a strip in the outer surface of the 'corrugated board;

By supporting the slitter knives closely adjoining the point at which the slit liner is adhered to the corrugated tend an .unslit portion of the liner sheet past the slitting rolls so that when the sheet is drawn taut the cut strip will be drawn into proper position upon the corrugated inner portion of the sheet. As the movement of the sheet neath the roll 44, it contacts a glue applying roller 49 progresses, thecut strip continues to be fed into proper position so that none of the corrugated inner portion of While I have described the various slitters as cutting entirely throughthe-liners,-- these* elements couldalsoact the principles of construction and operation of'my method for producing tear strips in corrugated board, and while I have endeavored to set forth the best embodiment thereof, I desire to-have it understood that obvious'changes may be made within the scope of the following claims without departing from the spirit of my invention.

I claim:

1. A method of manufacturing double-faced corrugated board having a tear strip. therein for use in container manufacture comprising continuously advancing two moving webs of material which are to form'liners, continuously advancing a web of material which is to form the corrugating medium, continuously corrugating said last-mentioned web along lines which extend transversely of the web to provide transverse flutes, continuously applying glue to all of the flutes on both sides of the corrugated web, continuously applying said liners to opposite sides of the corrugated web, and including the 'furthersteps- 0f slitting one of the moving liners on spaced longitudinally extending lines just prior to its being applied to the corrugated web to form longitudinal sections which are continuous, and maintaining said sections in their original relationship to each other prior to their being applied to the corrugatedweb.

2. A method of manufacturing double-faced corrugated board having a tear strip therein for use in container manufacture comprising continuously advancing two moving webs of material which are to form liners, continuously advancing a Web of material which is to'fo'rm the corrugating medium, continuously corrugating said lastmentioned web along lines which extend transversely of the web to provide transverse flutes, continuously apply- 7 ing webs of material which are to form liners, continu-" ously advancing a web of material which is to form the corrugating medium, continuously corrugating said lastmentioned web along lines which extend transversely of the web to provide transverse flutes, continuously applying glu to all of the flutes on bothsides of the corrugated Web, continuously applying said liners to opposite sides of the corugated 'web, and including the further a step of cutting spaced tear lines in each of the webs which is to form a liner just prior to its being applied to the corrugated web. i V

' 4. A method of manufacturing double-faced corrugated board having a tear strip therein for use in container manufacture comprising continuously advancing two moving webs of material which are to form liners, continuously advancing a web of material which is to form the corrugating medium, continuously corrugating said lastrnentioned web along lines which extend transversely of the web to provide transverse flutes, continuously slitting one of the webs which is to form a liner along spaced longitudinally extending lines to form longitudinal sections, thereafter continuously and uniformly gluing all of said longitudinal sections of said slit web to the flutes of the corrugated web on'one side thereof while maintaining said sections in their original relationship to each other, thereafter gluing the other 'web which is to form a liner to the flutes of the corrugated web on its other side.

5. A method of manufacturing double-faced corrugated board having a tear stn'p therein for use in container manufacture comprising continuously advancing two moving webs of material which are to form liners, continuously advancing a web of material which is to form the corrugating medium, continuously corrugating said lastmentioned web along lines which extend transversely of the web to provide transverse flutes, continuously gluing 10 one of the webs which is to form a liner to the flutes of the corrugated web on one of its sides, continuously slitting the web which is to form the other liner along spaced longitudinally extending lines to form longitudinal sec- 5 other.

References Cited in the file of this patent UNITED STATES PATENTS 2,475,052 Rosen July 5, 1949 2,544,020 Hoag Mar. 6, 1951 2,568,349 McKee Sept. 18, 1951 2,608,341 Eckman Aug. 26, 1952 2,679,349 Mullinix May 25, 1954 

